A broadcast transmitting system includes a first randomizer randomizing mobile service data bytes; a Reed-Solomon (RS) frame encoder generating an RS frame and dividing the RS frame into RS frame portions; a first interleaver interleaving symbols corresponding to data in the RS frame portions; a group formatter forming data groups including data corresponding to the interleaved symbols, each data group including known data sequences, signaling information, non-systematic RS parity data place holders and MPEG header data place holders; a packet formatter removing the non-systematic RS parity data place holders in the data groups and replacing the MPEG header data place holders in the data groups with Moving Picture Experts Group (MPEG) header data in order to output mobile service data packets; and a second randomizer randomizing the MPEG header data in the mobile service data packets.